Age resisting vulcanized rubber product



Patented Feb. 28,

I'NFIEL'D isoo'r'r,

LABQQATDRIES coi ora ikiior 01110,; ioonrom 'rion orionroi s fff AGEfnEsrs rnie yu'taczimziin ,mnziamp ZIRjODUCT i .HTh pat ent inv ntibnaiagt theihgnu;

facture ota vulcanized rubber product byan improved process whereino'theref is employed in additionto the ordinary compoundinginr 5 .gredients, a new type i of reaction product capablaof imparting, age resisting orant ir oxidant characteristics jto v the -rubber prod-2 It" is ,Wellknown, inthelart to which this '10 invention pertains that the use of cert'aiulor- R ganic compounds frequently is materially I limited because ofthe fact thatjthe presence of such compounds, or of ,theirheat of decomposition or sulfur or other reactionproducts produced in the curing process, apparently cause or aidin causing5'a' relatively rapid'ede 1 teriorationoftheyuleanized product s. Such rubber-products are said-to age badly, thatjis, the, rubber becomes hard and; loses a. large- V part'of its -re si1ie1icy, and other; characteris tics such as jteiisile strength, ultimate elongat-i'on and the, glike are detrimental'ly' affected.

Q ltghas now ibeen found-that the deterioration] of a vulcanized rubber compound may be substantiallydecreased ar d the. effective" life oftheproductmaterially lengthened if therebe added to the rubber compound, prior to vulcanization thereofla member of a class of materials formed by reacting substantially;v equi-molecular proportions 'of'an aryl hydroXide an aliphaticamine and an aliphatic aldehyde.

The age resisting characteristics of avulcanized rubber; productgcau be readily ascertained hy meansfof aii'acceleratedlaging test wherein samples of the vulcanized" product are subjected in bomb to the cti'dn ofio 'y- 1 gen runder pressure}audmaiutaiiied sev. eral hours ataii elevated temperature. '3 The 1'; "40. treatedisamples are thenexaiiiined and tested j and theresult's compared with similar;.results U st k; T eter et ie in meme e 1? fered as a resultof thelexposureto oxygen is indicative of the resultthat wouldi ormally .,;The:.present' invention will be derstood troni the following description and I I hereiu a preferredmode otoperating the inventionisset forth, v

. Onej of the prefer ed class of co po nd OEIINTTROQ EST vi eiivmyiissieivoaztro 'TfiE 'RUBBERI SERVICEL be expected fiomthat 'pz'irticular"stockldiibv 7 ing' service; 1 a ites'tis known as the- Bierer-l)ayisagiiig testand produces an effect onavulcar ized rubber stock comparable with that l resulting} from severalyears of f ie a i g ngiif tli rubberz y I (for e m l sfihe ew pr i et e l m tially equi=m0lecular proportions of pl enoL;

diethylamine; hand v 'fo 'iqnaldehyde pre- 7 pared in the, renew ng manner;

fil ed;imppmam elw fi her :Th

i ndpredl t iee o ssel di na c n trated hydrochloric 7 acid 1 and 'then made strongly alkaline by addingan excessrof an alkali;.foi example, sodium hydroxide 'solution. The light oil that separated out by lthis treatment"waspurified ,preferably by; dietil- I lation at a pressurelower than atmospheric pressure." The reaction. whereby the matei 'r'i'al hereiii'before described prepared 'fis A samp e of the reaction product prepared jas described was, incorporated in the well mariner- 1a rubberjstock comprising, i pare "bfrp crp u bee; P tS Q ans-. ewes-ems Q 1 E Pflfl-S if diphenyl-guanidine, 'and2.0 parts of the red action product of substantially e ui-molecular proportions of phenol, formal ehyde and diethylamine. a 7

The stock was then vulcanized by heating sheets of the stock in the'usual manner for by heating for 36 hours at'7 O "C. and under a pressure of 300 pounds of oxygen per square inch...- LThe results obtained upon test-f ing the agedfand the .unaged stocks are as follows:

Table I I. v

Modulus or alas ticilty mtlbslin tat E8 1. Time of cure l i 3235 V 8 ions. 0 break 52 123 x 7 a m a a 7 h lbs/in, tion 30mins. at 287 1 0 167 425 i040 2860 s00 30 mins. at 287 F 36 177 471 1790 2670 770 mins. at 287 F 0 210 620 2500 3545 760 45 131118. at 287 F; 36 214 708 2480 2890 735 From'the data set forth in Table I itis seen that the reaction product of-substantially equi-molecular proportions ofphenol, diethylamine and formaldehyde constitutes an anti-oxidant possessing desirable prop- "ertiesr Another example of the preferred class of compounds comprises a J reaction product of substantially equi molecular proportions of beta-naphthol," diethylamine and formaldehyde. This material was prepared in a man:

' ner'analogous to that previouslyfdescribed by which the reactionproduct', of phenol, formaldehyde and diethylamine. wasobtained. The reaction involved in the preparation of the reaction productof substan V tially equi=molecular proportions of betanaphthol, formaldehyde and diethylamine', is

most probably represented as follows:

A sample of the material thus prepared was compounded in theensual manner in a rubber mix comprising, 100 parts of pale crepe rubber, 5 parts of zinc oxide, 3.5 parts of sulfur, .8 parts of diphenyl-guanidine,

and 2.0 parts of the reaction product of substantially v beta-naphthol, diethylamine and formaldehyde.

j Therabovestock was vulcanizedlby heat ing at 287, F. for 30 and 45 minutes in a press and the vulcanized stock wasthen aged by heating for 36 hours at C. andunder equi-molecular "proportions of a pressure 'of 300 pounds of oxygen per square inch. The results obtained by testing the aged and unaged stocks follow:

,FI'OIII the datadisclosed in Table II it is apparent that a rubber'stock in which there is incorporated prior to vulcanization a reaction product of substantially equi-molecular proportions of an aryl hydroxide, an aliphatic amine and an aliphatic aldehyde, specifically a reaction product of substantially equi-molecular proportions of beta-naphthol,

formaldehyde and diethylamine, retains to a lar e-extent itsv original unaged characteristics. It is well known that a rubber stock containing the ingredients specified in the -foregoingexample with the exception that no anti-oxidant was employed melts down to a shapeless mass incapable of test when subjected to the artificial aging test as described.-

Other types of the preferred class ofcompounds, for example, the reaction product of substantiallyequi-molecular proportions of an aryl hydroxide, as for example henol, alpha and beta-naphthol, cresol'and the like, an aliphatic amine, such as methyl amine, ethylamine, dimethylamine, dieth lamine and analogous compounds and an a iphatic "aldehyde such as formaldehyde, acetalde- 'hyde,- crotonaldehyde, butylaldehyde and similar-aldehydes may be employed as antioxidants in a rubber mix of vulcanization characteristics. 7 i

The various examples hereinbefore set forth in detail are to be understood as illusooin momma-mo.

trative only and notat all limitative of the the art to which the inventionpertains. The i invention is to be understoodas limited solely by the claims attached hereto as a part of this specification, wherein the inventionis claimed as broadly as is possible in view of they prior art.

' v I 1,899,426 it What is claimed'is: i l I 1. The process of manufacturingavulcan ized rubber product -possessing age resisting characteristics which comprises heating rub ber and sulfur in the presence of an anti;

, oxidant comprising a reaction productof substantially equi-molecula'r I proportions of a mono-hydroxy substituted aromatic hydrocarbon, a straight chain aliphatic secondary amine containing less than fivecarbon :atoms and a saturated aliphatic aldehyde;

2. The process of manufacturing a vulcanized rubber product possessing age resisting. characteristics which comprises heating rubber and sulfur in the presence ofan antioxidant comprising a-reaction' product of substantially equi-molecular proportionsof a mono. hydroxy substituted aromatic hydrocarbon, a secondary aliphaticamine containsubstantially equi-inolecular proportions of c ing less than five carbon rated aliphatic aldehyde. v

3. The process of'manufacturing a vulcanized rubber product possessingage resisting charactristics which comprises heating rub-3 ber and sulfur in the presence-of an,anti-' oxidant comprising a, reaction product of substantially equi-molecular proportions of phenol, a straight chain secondary aliphatic amine containing less than five carbon atoms and a, saturated aliphatic aldehyde.

4'. The processor manufactur ng a Vulcan-'- ized rubber product possessinglage resisting characteristics which comprises heatingjrube ber and sulfurin the presence of {anantioxidant, comprising a (reaction; product of phenol,diethylamineand formaldehyde. I

5.'An ageresisting rubber product comprising the vulcanization product of. a rubber stock containing prior to the vulcanization r of said stockareaction: product of 's'ubs'tan atoms, and a' satustocklcontaining prior to the, vulcanization ofsaidstock" a reaction product of slibstana tially equi-molecular proportions of a mono 'h'ydr'oxy substituted aromatic hydrocarbon,

a secondary aliphatic amine containin less stock containing prior'to the, vulcanization.

of said stock a reaction ,product of substane, tially equi-molecular'pro ortions of phenol, diethylamine and formal ehyde.

In testimony whereof I hereuntoafiix my 7 Signature. V g

a I WINFIELD' SCOTTQ tially equi-molecularproportions of a'monoa hydroxy substituted aromatic hydrocarbon,

a straight chain aliphatic secondary "amine I containing less than five carbonatoms anda saturated aliphatic aldehyde.

6. An age resisting rubber product comprising the vulcanization product of a rub ber stock containing prior to the'vulcanizationof said stock a reaction product of subistantially equi-molecular: proportions of a.- mono hydroxy substituted aromatic ghydroe carbon, a saturated aliphatic secondary amine containing less than 'five carbon atoms and a saturatedaliphatic aldehyde. f 7. An age resisting rubber product com:

prising the vulcanization productiof arubber' stock containing prior 1 to the vulcanization of said stock a reaction product of substantially equi-molecular' proportions of phenol, j a straight chain,secondaryfaliphatic amine containing less than ,.five carbon, atoms and? a saturated aliphatic aldehyde.

8. An age resisting rubberrprod prising thevulcanization product ofa rubbergf no 7 Y DISCLAIMER 1,899,426.-Winfield Scott, Nitro; W. Va. AGE REsIsTINe VULCANIZED RUBBER PRODUCT. Patent dated February 2-8, 1933. Disclaimer filed May 31, 1935, by the assignee, The Rubber Service Laboratories Company.

Hereby disclaims that part of the claim in said specification which appears therein as claims 1, 2, 5, 6, and 8.

Your petitionerfurther says that the subject matter not herein and hereby disclaimed is definitely distinguishable from the part or parts disclaimed herein and is truly and justly'the invention of said Winfield Scott and is a material and substantial partpf the thing patented.

[Ofii'cz'al Gazette June 18, 1935.] 

